This paper describes test results of a joint NASA/Boeing research effort to advance Active Flow Control (AFC) technology to enhance aerodynamic efficiency. A full-scaleBoeing 757 vertical tail model equipped with sweeping jets AFC was tested at the National Full-Scale Aerodynamics Complex 40-by 80-Foot Wind Tunnel at NASA Ames Research Center. The flow separation control optimization was performed at 100 knots, a maximum rudder deflection of 30°, and sideslip angles of 0° and -7.5°. Greater than 20% increments in side force were achieved at the two sideslip angles with a 31-actuator AFC configuration. Flow physics and flow separation control associated with the AFC are presented in detail. AFC caused significant increases in suction pressure on the actuator side and associated side force enhancement. The momentum coefficient (C µ ) is shown to be a useful parameter to use for scaling-up sweeping jet AFC from sub-scale tests to full-scale applications. Reducing the number of actuators at a constant total C µ of approximately 0.5% and tripling the actuator spacing did not significantly affect the flow separation control effectiveness. NomenclatureAFC = active flow control APU = auxiliary power unit c = total local chord length CFD = computational fluid dynamics C p = pressure coefficient C y = side force coefficient C Yn = normalized side force coefficient relative to baseline (AFC off) C µ = momentum coefficient, % ERA = Environmentally Responsible Aviation LE = leading edge M ∞ = free stream Mach number NFAC = National Full-Scale Aerodynamics Complex Re = Reynolds number based on mean aerodynamic chord U ∞ = free stream velocity, knots x = streamwise direction β = sideslip angle, degrees δ Rudder = flap deflection angle, degrees %ΔC y = % difference in C y with respect to AFC off, 100%*(C y -C y, AFC off )/ C y, AFC off Downloaded by UNIVERSITY OF TORONTO on July 31, 2015 | http://arc.aiaa.org |
The formation and evolution of flow structures of a finite-span synthetic jet issuing into a quiescent flow were investigated experimentally using stereoscopic particle image velocimetry (SPIV). The effect of two geometrical parameters, the orifice aspect ratio and the neck length, were explored at a Strouhal number of 0.115 and a Reynolds number of 615. Normalized orifice neck lengths of 2, 4 and 6 and aspect ratios of 6, 12, and 18 were examined. It was found that the effect of the aspect ratio is much larger than the effect of the neck length, and as the aspect ratio increases the size of the edge vortices decreases and the presence of secondary structures is more evident. Moreover, axis switching was observed and its streamwise location increases as the aspect ratio increases. The effect of the neck length on the flow structures and the evolution of the synthetic jet was found to be secondary, where the effect was only in the very near field (i.e. close to the jet's orifice).
This paper describes wind tunnel test results from a joint NASA/Boeing research effort to advance active flow control (AFC) technology to enhance aerodynamic efficiency. A fullscale Boeing 757 vertical tail model equipped with sweeping jet actuators was tested at the National Full-Scale Aerodynamics Complex (NFAC) 40-by 80-Foot Wind Tunnel (40x80) at NASA Ames Research Center. The model was tested at a nominal airspeed of 100 knots and across rudder deflections and sideslip angles that covered the vertical tail flight envelope. A successful demonstration of AFC-enhanced vertical tail technology was achieved. A 31actuator configuration significantly increased side force (by greater than 20%) at a maximum rudder deflection of 30°. The successful demonstration of this application has cleared the way for a flight demonstration on the Boeing 757 ecoDemonstrator in 2015.
This paper presents the results of recent investigations into the aerodynamics of simulated runback ice accretion on airfoils. Aerodynamic testing was performed on a full-scale, 72-in.-chord (1828.8-mm-chord), NACA 23012 airfoil model over a Reynolds number range of 4:7 10 6 to 16:0 10 6 and a Mach number range of 0.10 to 0.28. A high-fidelity ice-casting simulation of a runback ice accretion was attached to the model leading edge. For Re 16:0 10 6 and M 0:20, the artificial ice shape decreased the maximum lift coefficient from 1.82 to 1.51 and decreased the stalling angle of attack from 18.1 to 15.0 deg. In general, the iced-airfoil performance was insensitive to Reynolds and Mach number changes over the range tested. Aerodynamic testing was also conducted on a quarter-scale NACA 23012 model [18 in. (457.2 mm) chord] at Re 1:8 10 6 and M 0:18, using low-fidelity geometrically scaled simulations of the full-scale casting. It was found that simple two-dimensional simulations of the upper-and lower-surface runback ridges provided the best representation of the full-scale, high-Reynolds-number, iced-airfoil aerodynamics. Higher-fidelity simulations of the runback ice accretion that included geometrically scaled three-dimensional features resulted in larger performance degradations than those measured on the full-scale model. Based upon this research, a new subclassification of spanwise-ridge ice is proposed that distinguishes between short and tall ridges. This distinction is made in terms of the fundamental aerodynamic characteristics as described in this paper. Nomenclature C d = drag coefficient C l = lift coefficient C l;max = maximum lift coefficient, coincident with stall C l; = lift-curve slope C m = quarter-chord pitching-moment coefficient c = airfoil chord length k = ice-roughness height or thickness M = freestream Mach number n = wall-normal distance above airfoil surface Re = Reynolds number based on chord U = mean streamwise velocity U 1 = freestream velocity u RMS = root-mean-square of fluctuating streamwise velocity x = chordwise position along airfoil y = normal position from airfoil chord line = airfoil angle of attack stall = stalling angle of attack, coincident with C l;max C d;rms = percent root-mean-square difference in C d
This paper summarizes a joint NASA/Boeing research effort to advance Active Flow Control (AFC) technology to enhance aerodynamic efficiency of a vertical tail. Sweeping jet AFC technology was successfully tested on subscale and full-scale models as well as in flight. The subscale test was performed at Caltech on a ~14% scale model. More than 50% side force enhancement was achieved by the sweeping jet actuation when the momentum coefficient was 1.7%. AFC caused significant increases in suction pressure on the actuator side and associated side force enhancement. Subsequently, a full-scale Boeing 757 vertical tail model equipped with sweeping jets was tested at the National Full-Scale Aerodynamics Complex 40-by 80-Foot Wind Tunnel at NASA Ames Research Center. There, flow separation control optimization was performed at near flight conditions. Greater than 20% increase in side force were achieved for the maximum rudder deflection of 30° at the key sideslip angles (0° and -7.5°) with a 31-actuator AFC configuration. Based on these tests, the momentum coefficient is shown to be a necessary, but not sufficient parameter to use for design and scaling of sweeping jet AFC from subscale tests to full-scale applications. Leveraging the knowledge gained from the wind tunnel tests, the AFC-enhanced vertical tail technology was successfully flown on the Boeing 757 ecoDemonstrator in the spring of 2015.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.